Distortion correction processing device, distortion correction method, and program

Abstract

To provide a distortion aberration correction processing device capable of performing distortion aberration correction with high accuracy even when an optical axis of an imaging device is slanted with respect to the surface of the object to be measured.SOLUTION: A storage unit stores distortion aberration correction information showing the relationship between a coordinate correction factor that corrects the coordinates on the image plane and a distance from a reference point for each of a plurality of sections divided by a plurality of boundaries extending radially from the reference point of the image plane of an imaging device. A processing unit selects at least one section from the plurality of sections on the basis of the coordinates in the image plane of a point to be corrected, determines the coordinate correction factor on the basis of the distortion aberration correction information for the selected section and the distance from the reference point to the point to be corrected, and corrects the coordinates of the point to be corrected on the basis of the determined coordinate correction factor.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a distortion correction processing device, a distortion correction method, and a program. [Background technology]

[0002] In an inkjet device that prints on an object by ejecting ink from an inkjet head, a laser processing device that drills holes in an object by irradiating a laser beam onto the object, and a laser annealing device that anneals a semiconductor substrate by irradiating a laser beam onto the object, the alignment mark provided on the object is detected to position the object. At this time, the position of the alignment mark is detected by performing image processing on an image showing the alignment mark.

[0003] In order to detect the position of the alignment mark with high accuracy, it is preferable to correct the distortion of the lens (for example, see Patent Document 1 below). In the distortion correction method disclosed in Patent Document 1, a five-dimensional polynomial correction formula is set as a function that converts the distance (image height) from the origin of the image plane to the distorted image to the distance before distortion. Using this polynomial equation, the distance after distortion is corrected to the distance before distortion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-133223 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the optical axis of the imaging device is tilted relative to the surface of the measurement target, the amount of distortion to be corrected changes depending on the circumferential position around the origin of the image plane. However, the correction method disclosed in Patent Document 1 corrects distortion only based on the distance from the origin of the image plane, so it is not possible to correct distortion with high accuracy when the optical axis of the imaging device is tilted.

[0006] An object of the present invention is to provide a distortion aberration correction processing device, a distortion aberration correction method, and a program that are capable of performing distortion aberration correction with high precision even when the optical axis of an imaging device is oblique to the surface of a measurement object. [Means for solving the problem]

[0007] According to one aspect of the present invention, When an xy Cartesian coordinate system is defined on the image plane of the imaging device, For each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point on the image plane, an x-coordinate correction factor for correcting the x-coordinate and a y-coordinate correction factor for correcting the y-coordinate; a storage unit in which distortion correction information indicating a relationship with the distance from the reference point is stored; At least one section is selected from the plurality of sections based on the coordinates of a correction target portion in the image plane, and a correction amount is calculated based on the distortion aberration correction information for the selected section and the distance from the reference point to the correction target portion. x-coordinate correction factor and y-coordinate correction factor decided and decided x-coordinate correction factor and y-coordinate correction factor A processing unit that corrects the coordinates of the correction target portion based on There is provided a distortion correction processing device comprising:

[0008] According to another aspect of the invention, When an xy Cartesian coordinate system is defined on the image plane of the imaging device, For each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point in the image plane, The x-coordinate correction factor for correcting the x-coordinate and the y-coordinate correction factor for correcting the y-coordinate an imaging device for which distortion aberration correction information indicating a relationship between the distance from the reference point and the measurement object is known; determining a correction target location for correcting coordinates within the image plane; selecting at least one section from the plurality of sections based on a position of the correction target portion in the image plane; Based on the distortion correction information for the selected section and the distance from the reference point to the correction target portion, x-coordinate correction factor and y-coordinate correction factor Determine, Decided x-coordinate correction factor and y-coordinate correction factor The present invention provides a distortion correction method for correcting the coordinates of the correction target portion based on the above-mentioned.

[0009] According to yet another aspect of the present invention, When an xy Cartesian coordinate system is defined on the image plane of the imaging device, For each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point in the image plane, The x-coordinate correction factor for correcting the x-coordinate and the y-coordinate correction factor for correcting the y-coordinate and acquiring an image of the measurement object captured using an imaging device for which distortion aberration correction information indicating a relationship between the image and the distance from the reference point is known; A step of determining a correction target portion to be corrected from an image captured by the imaging device; selecting at least one section from the plurality of sections based on coordinates of the correction target area in the image plane; Based on the distortion correction information for the selected section and the distance from the reference point to the correction target portion, x-coordinate correction factor and y-coordinate correction factor and a procedure for determining Decided x-coordinate correction factor and y-coordinate correction factor and correcting the coordinates of the correction target portion based on the A program for causing a computer to execute the above is provided. Effect of the Invention

[0010] By dividing the image plane into multiple sections and correcting distortion using distortion correction information set for each section, it is possible to perform distortion correction with high precision even when the optical axis of the imaging device is oblique to the surface of the object to be measured. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of a distortion correction processing device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the contents of the distortion aberration correction information. [Diagram 3] FIG. 3 is a graph for explaining a method of correcting the coordinates of the correction target portion in the image plane. [Figure 4] FIG. 4 is a flowchart showing a procedure for correcting the coordinates of the correction target area in the image plane. [Diagram 5] FIG. 5A is a diagram showing the distribution of images of multiple marks arranged in a matrix, captured using a telecentric lens, and FIG. 5B is a diagram showing the corrected coordinates of the marks calculated from the coordinates of the mark images using the method of this embodiment. [Figure 6] 6A and 6B are diagrams showing images of a mark in the image plane when it is assumed that there is no distortion and when it is assumed that there is distortion when the optical axis of the imaging device is perpendicular to the surface of the object to be measured, and FIG. 6C is a graph plotting the relationship between the coordinate correction factor Dx in the x-direction for the diagonal direction of the image plane and the distance r from the center point of the image plane. [Figure 7] 7A and 7B are diagrams showing images of a mark in the image plane when it is assumed that there is no distortion and when it is assumed that there is distortion, respectively, when the optical axis of the imaging device may be inclined with respect to the surface of the object to be measured. FIG. 7C is a graph plotting the relationship between the coordinate correction factor Dx in the x direction for the diagonal directions of the image plane and the distance r from the center point of the image plane, without distinguishing between the four diagonal directions of the image plane. FIG. 7D is a graph plotting the relationship between the coordinate correction factor Dx in the x direction for the diagonal directions of the image plane and the distance r from the center point of the image plane, distinguishing between each of the sections Q1 to Q4. [Figure 8] FIG. 8A is a schematic front view of an inkjet drawing device according to another embodiment, and FIG. 8B is a diagram showing the positional relationship in a plan view of a movable table, an ink ejection unit, and an imaging device. [Figure 9] FIG. 9 is a flowchart showing a procedure for performing drawing using the inkjet drawing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A distortion aberration correction processing device according to one embodiment will be described with reference to FIGS. FIG. 1 is a block diagram of a distortion aberration correction processing device 10 according to an embodiment. The distortion aberration correction processing device 10 according to this embodiment includes an input / output interface unit 11, a processing unit 12, and a storage unit 13. The processing unit 12 is, for example, a computer. The storage unit 13 stores a program 14 executed by the computer. The storage unit 13 further stores distortion aberration correction information 15. The contents of the distortion aberration correction information 15 will be described later with reference to FIG. 2. The storage unit 13 is, for example, an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD).

[0013] The processing unit 12 acquires image data from the imaging device 40 via the input / output interface unit 11. The processing unit 12 performs image analysis to detect the coordinates of the image of the alignment mark in the image. The coordinates of this image are affected by the distortion aberration of the lens and deviate from the actual coordinates indicating the position of the actual alignment mark. The processing unit 12 corrects the coordinates of the image using the distortion aberration correction information 15 stored in the storage unit 13 to reduce the error with the actual coordinates of the alignment mark. Thereafter, the corrected coordinates are passed to the control device 50 via the input / output interface unit 11. The control device 50 performs various processes based on the corrected coordinates of the alignment mark. The processing unit 12 and the control device 50 may be realized by a common computer. In this case, the processing unit 12 passes the corrected coordinates of the alignment mark to the control device 50 without going through the input / output interface unit 11.

[0014] 2 is a diagram showing the contents of the distortion aberration correction information 15. An xy Cartesian coordinate system with a reference point O as the origin is defined on an image plane 41 of the imaging device 40 (FIG. 1). Object points within the field of view of the imaging device 40 are transferred onto the image plane 41. The image plane 41 is, for example, a square or a rectangle, and the reference point O is the center of the square or the rectangle. The x-axis and y-axis are defined to be parallel to any side of the image plane 41.

[0015] The image surface 41 is divided into a plurality of sections Q1 to Q4 by a plurality of boundary lines BL extending radially from a reference point O. In the present embodiment, the boundary lines BL are lines connecting the reference point O and the midpoints of each side of the image surface 41. The four boundary lines BL correspond to the positive and negative parts of the x-axis and the positive and negative parts of the y-axis, and the sections Q1 to Q4 correspond to the first to fourth quadrants of the xy coordinate system, respectively.

[0016] Due to the influence of lens distortion, the position of an image point P1 corresponding to a certain observation point is shifted from the position of an image point P0 when it is assumed that the lens has no aberration. The distortion correction information 15 is information for correcting the coordinates of the image point P1 to obtain the coordinates of the image point P0 when there is no aberration, and the coordinate correction rate D in the x direction is x and the y-coordinate correction factor D y Includes.

[0017] Next, a method for obtaining the distortion aberration correction information 15 for the section Q1 will be described. An image of an object to be observed, on which a number of marks whose positions are known are formed, is captured by the imaging device 40 (FIG. 1) to obtain an image. The marks are, for example, lattice points of a lattice pattern. The object to be observed is moved until the image of the mark serving as the reference point of the object to be observed coincides with the reference point O on the image plane 41. For example, the image of the mark captured is analyzed to detect the position of the image of the mark, and the object to be observed is moved based on the detection result, thereby making it possible to match the image of the mark serving as the reference point with the reference point O on the image plane 41. This procedure may be repeated multiple times to improve the accuracy of the match between the two.

[0018] The obtained image is analyzed to extract multiple image points located on the diagonal line of section Q1, with reference point O at one end, from the image points of the multiple marks. One of the extracted multiple image points is denoted as P1. The image point without aberration that corresponds to image point P1 is denoted as P0. The coordinates of image point P1 are obtained by performing image analysis. The coordinates of image point P0 without aberration that corresponds to image point P1 are denoted as (x0, y0), and the coordinates of image point P1 are denoted as (x1, y1). Coordinate correction rate D in the x direction x and the y-coordinate correction factor D y is defined by the following formula:

number

[0019] Coordinate correction factor D in the x direction x is the ratio of the amount of displacement in the x direction, x1-x0, from image point P0 when there is no aberration to actual image point P1, to the length in the x direction, x0, from reference point O to image point P0 when there is no aberration. The coordinate correction rate in the y direction, Dy, is the ratio of the amount of displacement in the y direction, y1-y0, from image point P0 when there is no aberration to actual image point P1, to the length in the y direction, y0, from reference point O to image point P0 when there is no aberration. Generally, lens distortion is small at the center of the image surface and large at the periphery. For this reason, the coordinate correction rate D x , D y depends on the distance r from the reference point O.

[0020] The horizontal axis is the distance r from the reference point O to the actual image point P1, and the vertical axis is the coordinate correction factor D in the x direction. x The measurement results for multiple image points P1 on the diagonal line are plotted on a graph. An approximation curve that approximates the distribution of the multiple plotted points is determined. As a result, the coordinate correction rate D in the x direction for the section Q1 is calculated as shown in FIG. x is defined as a function of distance r. Similarly, the coordinate correction factor D y is also defined as a function of the distance r. In this way, the distortion correction information 15 for the section Q1 is obtained. In the graph of the distortion correction information 15 for the section Q1 shown in FIG. 2, the coordinate correction rate D x and the y-coordinate correction factor D y Examples of the above are shown by thick and thin solid lines, respectively.

[0021] In a similar manner, the distortion correction information 15 can be obtained for the other sections Q2 to Q4. The obtained distortion correction information 15 is stored in the storage unit 13 (FIG. 1). When the distortion does not depend on the radial direction from the reference point O, the coordinate correction factor D x , D y is almost the same among the sections Q1 to Q4. However, in reality, the coordinate correction rate D x , Dy varies among the sections Q1 to Q4. One of the causes of the variation is, for example, the inclination of the optical axis of the imaging device 40 with respect to the surface of the observation object.

[0022] Next, a method of correcting the coordinates of a certain location in the image plane 41 (hereinafter, referred to as a correction target location) to the coordinates in the absence of aberration will be described with reference to FIGS. Fig. 3 is a graph for explaining a method of correcting the coordinates of the correction target portion Pt on the image plane 41. Fig. 4 is a flowchart showing a procedure for correcting the coordinates of the correction target portion Pt on the image plane 41.

[0023] First, a correction target location Pt in the image plane 41 is determined. The correction target location Pt corresponds to, for example, the center point of the image of the alignment mark. Two sections are selected from the four sections Q1 to Q4 based on the position of the correction target location Pt (step S1). For example, of the boundaries BL separating the four sections Q1 to Q4, two sections on both sides of the boundary line BL that forms the smallest angle with the direction from the reference point O toward the correction target location Pt are selected. In FIG. 3, the positive portion of the y-axis corresponds to the boundary line BL that satisfies this condition. The two sections Q1 and Q2 on both sides of the positive portion of the y-axis are selected.

[0024] Next, based on the distortion correction information 15 (FIGS. 1 and 2) for the two selected sections Q1 and Q2, the coordinate correction rate D x , D y By weighting the average of these, the coordinate correction rate D xt (r), D yt For example, a weighted average is calculated based on the angle between the direction from the reference point O toward the geometric center of the two selected sections Q1 and Q2 (corresponding to the diagonal direction of the sections Q1 and Q2) and the direction from the reference point O toward the correction target point Pt.

[0025] When the angles between the direction from the reference point O toward the geometric center of the two selected sections Q1 and Q2 and the direction from the reference point O toward the correction target point Pt are denoted as θ1 and θ2, respectively, the coordinate correction rate D at the correction target point Pt is xt (r), D yt (r) is expressed by the following formula.

number

[0026] Next, the weighted average coordinate correction rate D xt , D yt Based on this, the coordinates of the correction target point Pt in the image plane are corrected (step S3). For example, when the coordinates of the correction target point Pt are expressed as (x1, y1) and the coordinates after correction are expressed as (x0, y0), the coordinates after correction are calculated using the following formula.

number

[0027] Next, the excellent effects of this embodiment will be described with reference to FIGS. 5A and 5B. Fig. 5A is a diagram showing the distribution of images of multiple marks arranged in a matrix, captured using a telecentric lens. Note that Fig. 5A shows the amount of deviation between the image of the marks when there is no aberration and the actual image, enlarged 100 times. Fig. 5A shows that barrel distortion occurs.

[0028] Fig. 5B is a diagram showing the coordinates of the corrected image of the mark calculated from the coordinates of the actual image of the mark using the method of this embodiment. Fig. 5B also shows the deviation amount from the image of the mark without aberration to the image after the coordinate adjustment, enlarged by 100 times. As shown in Fig. 5B, it can be seen that the distortion aberration is corrected and a distribution close to the original matrix arrangement is obtained.

[0029] In this way, by using the method according to the above embodiment, the distortion of the lens can be corrected and the coordinates of the mark image can be brought closer to the coordinates without aberration.

[0030] Next, with reference to FIGS. 6A to 6C and 7A to 7D, the reason why distortion aberration can be corrected with high accuracy even when the optical axis of imaging device 40 (FIG. 1) is tilted with respect to the surface of the object to be measured will be described.

[0031] 6A and 6B are diagrams showing images of marks in image plane 41 when it is assumed that there is no distortion and when there is distortion, respectively, when the optical axis of imaging device 40 is perpendicular to the surface of the measurement object. The horizontal and vertical axes of Fig. 6A and Fig. 6B represent positions in the x and y directions, respectively. A number of marks are arranged at the lattice points of the lattice pattern. In Fig. 6A and Fig. 6B, the images of the marks are indicated by blackened circles.

[0032] If it is assumed that there is no distortion, the positions of the images of the multiple marks coincide with the lattice points of a square lattice, as shown in Fig. 6A. If it is assumed that there is distortion, the positions of the images of the marks deviate from the lattice points, as shown in Fig. 6B. In Fig. 6B, it is assumed that barrel distortion, which is significantly larger than the distortion of a general lens, occurs.

[0033] FIG. 6C shows the x-direction coordinate correction factor D xThis is a graph in which the relationship between the distance r from the center point of the image plane and the angle θ is plotted without distinguishing between the four diagonal directions. Since distortion has low dependency on the direction of rotation around the center point of the image plane, the multiple measurement points plotted in the four diagonal directions can be accurately approximated by a single approximation curve.

[0034] 7A and 7B are diagrams showing images of marks in image plane 41 when it is assumed that there is no distortion and when there is distortion, respectively, when the optical axis of imaging device 40 is tilted with respect to the surface of the measurement object. The horizontal and vertical axes of Fig. 7A and Fig. 7B represent positions in the x and y directions, respectively. A number of marks are arranged at the lattice points of the lattice pattern. In Fig. 7A and Fig. 7B, the images of the marks are indicated by blackened circles.

[0035] Because the optical axis of the imaging device 40 is tilted, the position of the mark image is shifted from the grid point, as shown in Fig. 7A, even if it is assumed that there is no distortion. Because there is no distortion, the image of a straight line on the measurement object will also be a straight line in the image plane. For example, if the perimeter of the area where multiple marks are distributed is a square, the perimeter of the area where the mark images are distributed in the image plane 41 will be a trapezoid.

[0036] If it is assumed that the same distortion aberration as that shown in FIG. 6B occurs in the distribution of the mark images shown in FIG. 7A, the area in which the mark images are distributed when it is assumed that distortion aberration exists will have a shape that resembles a combination of a trapezoid and a barrel shape, as shown in FIG. 7B.

[0037] FIG. 7C shows the coordinate correction factor D in the x direction for the diagonal directions of the image plane 41 without distinguishing between the four diagonal directions of the image plane 41. x 6 is a graph plotting the relationship between the distance r from the center point of the image plane 41 and the magnitude and direction of the distortion aberration differ between the diagonal directions, so the plotted measurement points are distributed over a wider range in the vertical axis direction than in the case shown in FIG. 6C. Even if a single approximation curve is set for this distribution, there is a large error between the coordinate correction factor determined from the approximation curve and the coordinate correction factor at each measurement point.

[0038] FIG. 7D shows the coordinate correction factor D in the x direction in the diagonal direction of the image plane 41, distinguishing each of the sections Q1 to Q4. x 7D is a graph plotting the relationship between the distance r from the center point of the image plane and the square symbol, the triangle symbol, and the circle symbol in the graph are plotted for the measurement points located on the diagonal lines of the sections Q2, Q3, and Q4, respectively. Note that the coordinate correction factor is also calculated for multiple measurement points in the section Q1, but the measurement points are not shown in FIG. 7D.

[0039] 7D are approximation curves that approximate the distribution of the measurement points of the coordinate correction factor in the x direction for the sections Q1 to Q4. When focusing on one section, the error between the coordinate correction factor calculated from the approximation curve and the coordinate correction factor at multiple measurement points is small.

[0040] When the optical axis of the imaging device 40 is inclined with respect to the surface of the measurement object, if the coordinates of the correction target portion are corrected based on one approximation curve shown in Fig. 7C, the error between the corrected coordinates and the aberration-free coordinates increases depending on the position of the correction target portion. In response to this, in this embodiment, in step S1 (Fig. 4), two approximation curves that more accurately reflect the coordinate correction rate at the correction target portion are selected from the four approximation curves shown in Fig. 7D.

[0041] Furthermore, in step S2 (FIG. 4), the coordinate correction factors obtained from the two approximation curves are weighted and averaged according to the degree to which the coordinate correction factor at the correction target location is reflected. Therefore, even if the optical axis of the imaging device 40 is inclined with respect to the surface of the measurement target, the coordinates can be corrected using a coordinate correction factor close to the actual coordinate correction factor at the correction target location. Therefore, the accuracy of the coordinate correction can be improved.

[0042] Next, a modification of the above embodiment will be described. In the above embodiment, the image surface 41 (FIG. 2) is divided into four sections Q1 to Q4, but the number of sections is not limited to four. The number of sections may be two or more. For example, in the example shown in FIG. 7D, the approximation curves of the sections Q1 and Q4 are mutually approximate, and the approximation curves of the sections Q2 and Q3 are mutually approximate. Therefore, even if the sections Q1 and Q4 are combined into one section, and the sections Q2 and Q3 are combined into one section, the coordinate correction accuracy can be maintained at a relatively high level.

[0043] In the above embodiment, the coordinate correction ratios are calculated for the image points P1 (FIG. 2) on the diagonal lines of each of the four sections Q1 to Q4, and one approximation curve is set based on the coordinate correction ratios. The image points P1 on which the approximation curve is set may not be limited to those on the diagonal lines, but may be set by taking into consideration the coordinate correction ratios of other image points P1 in the section.

[0044] For example, the coordinate correction ratio may be calculated for a plurality of image points P1 in an area sandwiched between two radial directions extending from the reference point O into one section. In this case, in order to set one approximation curve that strongly reflects the coordinate correction ratios at the plurality of image points P1 in the section, it is preferable to set the two radial directions so that the area sandwiched between the two radial directions includes the geometric center of the section.

[0045] In the above embodiment, when selecting two sections in step S1 (FIG. 4), two sections are selected on both sides of the boundary line BL that, among the four boundary lines BL, forms the smallest angle with the direction from the reference point O toward the correction target point Pt. Alternatively, two sections that closely approximate the coordinate correction rate at the correction target point Pt with high accuracy may be selected.

[0046] For example, in the example shown in FIG. 7D, the approximation curve of the section Q1 and the approximation curve of the section Q4 show similar trends with respect to the change in distance r. This means that when the correction target portion Pt is located in the section Q1 or the section Q4, the coordinate correction rate in the correction target portion Pt is approximated with high accuracy in the sections Q1 and Q4. Therefore, when the correction target portion Pt is located in the section Q1 or the section Q4, it is preferable to select the sections Q1 and Q4 as the two sections in step S1 (FIG. 4). For the same reason, when the correction target portion Pt is located in the section Q2 or the section Q3, it is preferable to select the sections Q2 and Q3 as the two sections in step S1 (FIG. 4).

[0047] In the above embodiment, two sections are selected in step S1 (FIG. 4), but one section may be selected. For example, when the angle θ1 (FIG. 3) is 0° or sufficiently small, only section Q1 may be selected. Whether one section or two sections are selected may be determined based on the magnitude of the angle θ1.

[0048] Next, an inkjet drawing device according to another embodiment will be described with reference to Figures 8A, 8B, and 9. The inkjet drawing device according to this embodiment is equipped with the distortion aberration correcting device according to the embodiment shown in Figures 1 to 4.

[0049] 8A is a schematic front view of the inkjet drawing device 20. A movable table 25 is supported on a base 22 by a moving mechanism 24. An xyz Cartesian coordinate system is defined in which the x-axis and y-axis are oriented horizontally and the z-axis is oriented vertically downward. The moving mechanism 24 is controlled by a control device 50 to move the movable table 25 in two directions, the x-direction and the y-direction. As the moving mechanism 24, for example, an XY stage including an X-direction moving mechanism 24X and a Y-direction moving mechanism 24Y can be used.

[0050] A substrate 80, which is an object to be drawn, is held on the upper surface of the movable table 25. The substrate 80 is fixed to the movable table 25 by, for example, a vacuum chuck. Above the movable table 25, an ink ejection unit 30 and an imaging device 40 are supported by, for example, a gate-shaped support member 23.

[0051] The imaging device 40 captures an image of the upper surface of the substrate 80. More specifically, the imaging device 40 captures an image of a region of the upper surface of the substrate 80 that is within the field of view of the imaging device 40. The image obtained by the imaging device 40 is input to the distortion aberration correction processing device 10.

[0052] The control device 50 receives position information of the substrate 80 from the distortion aberration correction processing device 10. By controlling the movement mechanism 24 and the ink ejection unit 30 based on this position information, ink is caused to land at a predetermined position on the surface of the substrate 80. As a result, an ink film of a predetermined shape is formed on the surface of the substrate 80.

[0053] 8B is a diagram showing the positional relationship in a plan view among the movable table 25, the ink ejection unit 30, and the imaging device 40. A substrate 80 is held on the upper surface of the movable table 25. The ink ejection unit 30 and the imaging device 40 are supported above the substrate 80. A plurality of nozzles 32 are provided on the surface of the ink ejection unit 30 facing the substrate 80. The control device 50 controls the movement mechanism 24 to move the movable table 25 in the x and y directions, and also controls the ejection of ink from each nozzle 32 of the ink ejection unit 30.

[0054] Alignment marks 81 are formed at each of the four corners of the substrate 80. The control device 50 operates the moving mechanism 24 to position each of the alignment marks 81 within the field of view of the imaging device 40, thereby enabling the imaging device 40 to capture an image of the alignment marks 81.

[0055] 9 is a flow chart showing the procedure for drawing with the inkjet drawing device. First, the control device 50 operates the moving mechanism 24 to move one alignment mark 81 into the field of view of the imaging device 40 (step S11). After that, the imaging device 40 captures an image of the alignment mark 81 (step S12). The captured image data is input to the distortion aberration correction processing device 10. The distortion aberration correction processing device 10 analyzes the image of the alignment mark 81 to detect the coordinates of the image of the alignment mark 81 in the image plane (step S13). A known algorithm such as pattern matching can be used to detect the coordinates of the image of the alignment mark 81.

[0056] The distortion aberration correction processing device 10 corrects the coordinates of the image of the alignment mark 81 (step S14) by executing the procedure according to the embodiment shown in Fig. 4. The procedure from step S11 to step S14 is repeated until the coordinate correction is performed for all alignment marks 81 (step S15).

[0057] When the coordinate correction is completed for all alignment marks 81, the distortion aberration correction processing device 10 passes the corrected coordinates of the images of the alignment marks 81 to the control device 50 (FIGS. 8A and 8B) (step S16). The control device 50 executes the drawing process based on the corrected coordinates of the images of the alignment marks 81 (step S17).

[0058] Next, the excellent effects of this embodiment will be described. 1 to 4, the inkjet drawing apparatus according to this embodiment is capable of measuring the position of the alignment mark 81 with high accuracy. In particular, even if the optical axis of the imaging device 40 is inclined with respect to the surface of the substrate 80, a decrease in the measurement accuracy of the position of the alignment mark 81 can be suppressed.

[0059] Next, a modified example of the embodiment shown in Figures 8A to 9 will be described. In the embodiment shown in Figures 8A to 9, the distortion aberration correction processing device 10 according to the embodiment shown in Figures 1 to 4 is mounted on an inkjet drawing device, but the distortion aberration correction processing device 10 according to the embodiment shown in Figures 1 to 4 can also be mounted on other devices. For example, it can also be mounted on a laser processing device that irradiates a laser beam on an object to perform hole drilling, or a laser annealing device that irradiates a laser beam on a semiconductor substrate, which is an object, to perform annealing.

[0060] The above-mentioned embodiments are merely examples, and it goes without saying that partial replacement or combination of the configurations shown in different embodiments is possible. Similar effects due to similar configurations of multiple embodiments are not mentioned in each embodiment. Furthermore, the present invention is not limited to the above-mentioned embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible. [Explanation of symbols]

[0061] 10 Distortion correction processing device 11 Input / Output Interface Section 12 Processing section 13 Storage section 14 Program 15 Distortion correction information 20 Inkjet drawing device 22 Foundation 23 Support member 24 Moving mechanism 24X X direction movement mechanism 24Y Y direction movement mechanism 25 Movable Table 30 Ink ejection unit 32 Nozzles 40 Imaging device 41 Image plane of imaging device 50 Control device 80 Substrate 81 Alignment Mark

Claims

1. A memory unit in which, when an xy Cartesian coordinate system is defined on an image plane of an imaging device, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point on said image plane, is stored distortion aberration correction information indicating the relationship between an x-coordinate correction factor for correcting the x-coordinate on said image plane, a y-coordinate correction factor for correcting the y-coordinate on said image plane, and a distance from said reference point; a processing unit that selects at least one section from the plurality of sections based on coordinates of a correction target portion in the image plane, determines an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and a distance from the reference point to the correction target portion, and corrects the coordinates of the correction target portion based on the determined x-coordinate correction rate and y-coordinate correction rate; A distortion correction processing device comprising:

2. the shape of the image surface is square or rectangular; the reference point is located at the center of the image plane; 2. The distortion aberration correction processing device according to claim 1, wherein the plurality of boundary lines are four line segments connecting the center of the image plane to the midpoints of the four sides.

3. The processing unit, in the process of correcting the coordinates of the correction target portion, selecting two sections on both sides of a boundary line that forms a smallest angle with a direction from the reference point toward the correction target portion from among the plurality of boundary lines; 3. The distortion aberration correction processing device according to claim 1, further comprising: a weighted average of x-coordinate correction rates and y-coordinate correction rates of the distortion aberration correction information for the two selected sections based on an angle between a direction from the reference point toward a geometric center of each of the two selected sections and a direction from the reference point toward the correction target location; and a correction unit for correcting the coordinates of the correction target location based on the weighted average of the x-coordinate correction rate and the y-coordinate correction rate.

4. When an xy Cartesian coordinate system is defined on the image plane of an imaging device, an object to be measured is imaged using an imaging device in which distortion aberration correction information indicating the relationship between an x-coordinate correction factor for correcting an x-coordinate in an image and a y-coordinate correction factor for correcting a y-coordinate in an image, and a distance from a reference point, for each of a plurality of sections separated by a plurality of boundaries extending radially from a reference point in the image plane, is known; determining a correction target location for correcting coordinates within the image plane; selecting at least one section from the plurality of sections based on a position of the correction target portion within the image plane; determining an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and the distance from the reference point to the correction target location; The distortion aberration correcting method corrects the coordinates of the correction target portion based on the determined x-coordinate correction rate and y-coordinate correction rate.

5. A step of acquiring an image of a measurement object captured using an imaging device in which, when an x-y Cartesian coordinate system is defined on the image plane of an imaging device, distortion aberration correction information indicating the relationship between an x-coordinate correction factor that corrects the x-coordinate in the image and a y-coordinate correction factor that corrects the y-coordinate in the image, and a distance from the reference point, is known for each of a plurality of sections separated by a plurality of boundaries extending radially from a reference point in the image plane; A step of determining a correction target portion to be corrected from an image captured by the imaging device; selecting at least one section from the plurality of sections based on coordinates of the correction target area in the image plane; determining an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and a distance from the reference point to the correction target location; correcting the coordinates of the correction target portion based on the determined x-coordinate correction rate and y-coordinate correction rate; A program that causes a computer to execute the following.

Images